1. Technical Field
Embodiments generally relate to electronic circuits and, more specifically, to circuits using encryption, signature, and other keys, derived from a master or basic key contained in the electronic circuit.
2. Discussion of the Related Art
Most electronic circuits using keys used by algorithms of signature or encryption, or other cryptographic elements, use key derivation mechanisms to limit the exposure (the number of uses) of a basic key of the circuit. Such techniques especially enable to repudiate (to consider as invalid) keys used too often or supposed to have been attacked, and to regenerate new keys for subsequent sessions. In particular, frequently, for each new session of a cryptographic process, the electronic circuit generates a session key by deriving the basic key.
A limitation of such mechanisms is that the basic key is exposed each time a session key is derived, which makes it indirectly sensitive to certain attacks such as, for example, side channel analyses of differential power analysis (DPA) type.
Further, if it is decided to limit the number of uses of the basic key, this also limits the number of session keys that may be derived for the circuit.